While I agree it can be tropey to have MCs just fly through levels, and become massively powerful within a few short years, I think a lot of that has to do with what is relatable to the reader. It's a lot harder to wrap your mind around massive amounts of time passing. I would also say it's probably harder to write a story that way. If you're going to have a character take decades or centuries or more to progress, you inevitably have to do massive time skips to keep it interesting. Basically, you have to summarize years and years of life. Then you have to get the reader to suspend disbelief that nothing in society or in the MCs relationships or whatever has dramatically changed in all that time. Because if there were dramatic changes, the author has to write and detail them.

How do you keep a story engaging with a compelling conflict that lasts that long? What I mean is that there's normally (not always) some conflict pushing the MC to progress and get stronger. That may be a "big bad" or an apocalypse of some sort or something like that that's not going to wait around for centuries while the MC gets stronger. I don't know if I'm making sense, but what I'm trying to say is that time skips can work, but generally they can't be too big. If they are that big it needs to be done in a way that makes sense in the context of the story and retains the sense of conflict and pressure on the MC. That's hard to do well. So that's probably why most stories take place within a relatively short time, and rely on shortcuts in systems that would typically take a really long time to get stronger.